Background: Triple negative breast cancer (TNBC) has several subtypes. Identification of markers associated with recurrence and poor prognosis in TNBC patients is critically needed. BRCAness is a set of traits in which BRCA1 dysfunction, arising from gene mutation, methylation or deletion, results in DNA repair deficiency. In the present study we evaluated the clinical significance and prognosis of BRCAness in a multicenter retrospective study.

Methods: Ninety-four TNBC patients treated with neoadjuvant chemotherapy (NAC) were enrolled from three hospitals in Japan for this retrospective study. Of these patients, 86 (91.5%) were treated with anthracyclines and taxanes. BRCAness was determined from 94 core needle biopsy (CNB) specimens prior to NAC and 50 surgical specimens without pathological complete response (pCR). The samples were assessed using multiplex ligation-dependent probe amplification (MLPA) and the amplicons were scored. Samples with scores >0.5 were defined as having BRCAness.

Results: Of the 94 TNBC patients, 51 (54.3%) had BRCAness in CNB specimens. There were no significant differences in pCR rate or recurrence between the BRCAness and non-BRCAness groups. Among surgical specimens, the BRCAness group (19/50, 38%) had a significantly shorter recurrence-free survival (RFS) and disease-specific survival (DSS) compared with the non-BRCAness group (p < 0.01 and p < 0.05). The BRCAness group had independent prognostic factors for recurrence and survival in multivariate regression analysis.

Conclusions: The BRCAness of surgical specimens is a useful marker to predict prognosis in TNBC patients after NAC. A clinical trial to assess the clinical impact of platinum-containing drugs with BRCAness is planned.

Citation Format: Kosaka Y, Yamamoto Y, Nishimiya H, Ibusuki-Yamamoto M, Hirota Y, Tanino H, Iwase H, Nakamura S, Akashi-Tanaka S. BRCAness as a prognostic marker in triple-negative breast cancer patients treated with neoadjuvant chemotherapy: A multicenter retrospective study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-06.